SPT Testing in Newark: Real Soil Data for Foundation Design

A five-story mixed-use project on Ferry Street hit refusal at 12 feet. The contractor had no idea there was a buried foundation from the 1920s under the lot. We see this pattern across Newark — the subsurface is rarely what the surface suggests. The city sits on glacial sediment and historic fill, with depth-to-rock varying wildly between the Ironbound and the North Ward. In our experience, SPT data is the only reliable way to map these transitions before the excavator bucket finds them first. We run the Standard Penetration Test to ASTM D1586, correlating blow counts with soil behavior so the structural engineer isn't guessing. When the bore log shows N-values dropping below 4 in the Meadowlands area, we flag it immediately. That's the difference between a foundation that holds and one that settles unevenly within the first two years.

N-values below 4 in the Meadowlands formation demand immediate foundation redesign — we flag it the same day the bore log is completed.

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How we work

Newark's expansion from colonial port to industrial powerhouse left a complex stratigraphy beneath the streets. Much of the downtown sits on compacted fill layered over varved clays and glacial till. The SPT captures this layering with a resolution that CPT alone can miss when gravel or demolition debris is present. Our field crews log every split-spoon sample visually before it goes to the lab. We cross-reference N-values with the Unified Soil Classification System per ASTM D2487, giving the design team a clear picture of bearing capacity and liquefaction potential. When fill thickness exceeds 15 feet, as it often does near the Passaic River, we coordinate the SPT program with a test pit investigation to expose the fill-to-natural transition directly. For deeper sections where continuous profiling is needed, the data pairs well with a CPT sounding to fill in the gaps between SPT intervals.

SPT Testing in Newark: Real Soil Data for Foundation Design — Technical reference — Newark

Local geotechnical context

The Meadowlands substrata and the buried valleys beneath Newark present a liquefaction risk that ASCE 7 requires addressing for Seismic Design Category D. Fine sands and silts with N-values below 15 are common at depths of 15 to 35 feet. When saturated, these layers can lose strength during a design-level earthquake. We calculate the liquefaction potential index directly from SPT blow counts using the Seed and Idriss simplified procedure. Another hazard is uncontrolled fill containing brick, slag, and wood fragments. N-values in this material can be erratic, and refusal on buried obstructions is routine. The Passaic River waterfront adds a high groundwater table to the equation. SPT data from a water-filled borehole, if not properly cased, will give misleading N-values. We case every hole through the water column to keep the data clean and defensible.

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Relevant standards

ASTM D1586-18, ASTM D2487-17e1, ASTM D4633-16, IBC 2021 Section 1803, ASCE 7-22 Chapter 20

Technical data

Parameter	Typical value
Standard reference	ASTM D1586-18
Hammer type	Safety hammer with energy calibration
Borehole diameter	4 in (NX) or 6 in (HX) as required
Sampling interval	Every 5 ft and at stratum change
N-value correction	Energy ratio (ER) per ASTM D4633
Soil classification	USCS per ASTM D2487
Typical depth range in Newark	40 to 120 ft below grade
Reporting	Bore logs with SPT N, soil description, and groundwater observation

Common questions

What does an SPT test in Newark typically cost?

For a standard program of two to three boreholes to depths of 40 to 60 feet, the cost ranges from US$630 to US$820 per borehole depending on access conditions and traffic control requirements. Deeper holes, confined entry sites, or night work in the Ironbound district will push toward the upper end of that range.

How many boreholes does the IBC require for a commercial building in Newark?

IBC Section 1803 requires at least one borehole for every 2,500 square feet of building footprint, with a minimum of two for any structure. For sites within the Meadowlands influence zone or where historic fill is suspected, the geotechnical engineer of record will typically specify a tighter spacing to capture lateral variability in the fill thickness and the depth to competent bearing stratum.

Can SPT data alone confirm if a Newark site needs deep foundations?

In most cases yes, but not always. If SPT N-values consistently fall below 10 in the upper 30 feet and the structure carries heavy column loads, deep foundations will almost certainly be required. However, if the refusal depth is shallow and erratic, as it often is near the old industrial corridors, a complementary test pit program helps confirm whether the refusal is bedrock or a buried obstruction before committing to a pile design.

Location and service area

We serve projects in Newark and surrounding areas. More info.

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